In an accelerator apparatus of an electronic type, the amount of depression of an accelerator pedal is sensed with a sensor, and the sensor outputs an electrical signal, which indicates the sensed amount of depression of the accelerator pedal, to an electronic control device. The electronic control device drives a throttle valve based on the sensed amount of depression of the accelerator pedal and other information.
JP2010-158992A teaches an accelerator apparatus of an electronic type, which includes a pedal rotor and a return rotor that are rotatably supported by a shaft. An accelerator pedal, which is depressible by a foot of a driver of the vehicle, is connected to the pedal rotor to rotate integrally therewith. When the accelerator pedal is depressed by the foot of the driver to rotate the pedal rotor from an accelerator-full-closing position, which corresponding to an idling state of an engine, in an accelerator-opening direction, the pedal rotor and the return rotor are urged away from each other in an axial direction of the shaft.
In the state where the pedal rotor and the return rotor are urged away from each other in the axial direction of the shaft, the pedal rotor axially urges a first friction member, which is fixed to the pedal rotor, against the support member. Thereby, the pedal rotor receives a resistance torque through the first friction member. Furthermore, the return rotor urges a second friction member, which is axially placed between the return rotor and the support member, against the support member. Thereby, the return rotor receives a resistance torque through the second friction member. These resistance torques act to maintain the rotation of the accelerator pedal connected to the pedal rotor and generate the pedal force hysteresis characteristics such that the pedal force, which is applied to the accelerator pedal at the time of releasing the accelerator pedal, is smaller than the pedal force, which is applied to the accelerator pedal at the time of depressing the accelerator pedal.
In the accelerator apparatus of JP2010-158992A, when a foreign object is clamped between the first friction member and the support member or between the return rotor and the second friction member or when the frictional force of each friction member is increased due to an environmental change, the first friction member may be fastened (jammed) to the support member, and/or the second friction member may be fastened (jammed) to the return rotor. When at least one of the first friction member and the second friction member is fastened, the accelerator pedal may not be returned to the accelerator-full-closing position. Thereby, in such a state, when the depressed accelerator pedal is released by removing the foot of the driver from the accelerator pedal, the engine may not be returned to the idling state.